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Peter Anvin" , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v8 14/15] KVM: xen: split up kvm_xen_set_evtchn_fast() Date: Tue, 21 Nov 2023 18:02:22 +0000 Message-Id: <20231121180223.12484-15-paul@xen.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20231121180223.12484-1-paul@xen.org> References: <20231121180223.12484-1-paul@xen.org> MIME-Version: 1.0 X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lipwig.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (lipwig.vger.email [0.0.0.0]); Tue, 21 Nov 2023 10:31:14 -0800 (PST) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1783199409255001034 X-GMAIL-MSGID: 1783199409255001034 From: Paul Durrant The implementation of kvm_xen_set_evtchn_fast() is a rather lengthy piece of code that performs two operations: updating of the shared_info evtchn_pending mask, and updating of the vcpu_info evtchn_pending_sel mask. Introdude a separate function to perform each of those operations and re-work kvm_xen_set_evtchn_fast() to use them. No functional change intended. Signed-off-by: Paul Durrant Reviewed-by: David Woodhouse --- Cc: Sean Christopherson Cc: Paolo Bonzini Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" Cc: David Woodhouse Cc: x86@kernel.org v8: - New in this version. --- arch/x86/kvm/xen.c | 170 +++++++++++++++++++++++++-------------------- 1 file changed, 96 insertions(+), 74 deletions(-) diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index 42a9f1ea25b3..eff405eead1c 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -1623,60 +1623,28 @@ static void kvm_xen_check_poller(struct kvm_vcpu *vcpu, int port) } } -/* - * The return value from this function is propagated to kvm_set_irq() API, - * so it returns: - * < 0 Interrupt was ignored (masked or not delivered for other reasons) - * = 0 Interrupt was coalesced (previous irq is still pending) - * > 0 Number of CPUs interrupt was delivered to - * - * It is also called directly from kvm_arch_set_irq_inatomic(), where the - * only check on its return value is a comparison with -EWOULDBLOCK'. - */ -int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, struct kvm *kvm) +static int set_shinfo_evtchn_pending(struct kvm_vcpu *vcpu, u32 port, u32 *port_word_bit) { + struct kvm *kvm = vcpu->kvm; struct gfn_to_pfn_cache *gpc = &kvm->arch.xen.shinfo_cache; - struct kvm_vcpu *vcpu; unsigned long *pending_bits, *mask_bits; unsigned long flags; - int port_word_bit; - bool kick_vcpu = false; - int vcpu_idx, idx, rc; - - vcpu_idx = READ_ONCE(xe->vcpu_idx); - if (vcpu_idx >= 0) - vcpu = kvm_get_vcpu(kvm, vcpu_idx); - else { - vcpu = kvm_get_vcpu_by_id(kvm, xe->vcpu_id); - if (!vcpu) - return -EINVAL; - WRITE_ONCE(xe->vcpu_idx, vcpu->vcpu_idx); - } - - if (!vcpu->arch.xen.vcpu_info_cache.active) - return -EINVAL; - - if (xe->port >= max_evtchn_port(kvm)) - return -EINVAL; - - rc = -EWOULDBLOCK; - - idx = srcu_read_lock(&kvm->srcu); + int rc = -EWOULDBLOCK; read_lock_irqsave(&gpc->lock, flags); if (!kvm_gpc_check(gpc, PAGE_SIZE)) - goto out_rcu; + goto out; if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) { struct shared_info *shinfo = gpc->khva; pending_bits = (unsigned long *)&shinfo->evtchn_pending; mask_bits = (unsigned long *)&shinfo->evtchn_mask; - port_word_bit = xe->port / 64; + *port_word_bit = port / 64; } else { struct compat_shared_info *shinfo = gpc->khva; pending_bits = (unsigned long *)&shinfo->evtchn_pending; mask_bits = (unsigned long *)&shinfo->evtchn_mask; - port_word_bit = xe->port / 32; + *port_word_bit = port / 32; } /* @@ -1686,52 +1654,106 @@ int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, struct kvm *kvm) * already set, then we kick the vCPU in question to write to the * *real* evtchn_pending_sel in its own guest vcpu_info struct. */ - if (test_and_set_bit(xe->port, pending_bits)) { + if (test_and_set_bit(port, pending_bits)) { rc = 0; /* It was already raised */ - } else if (test_bit(xe->port, mask_bits)) { - rc = -ENOTCONN; /* Masked */ - kvm_xen_check_poller(vcpu, xe->port); + } else if (test_bit(port, mask_bits)) { + rc = -ENOTCONN; /* It is masked */ + kvm_xen_check_poller(vcpu, port); } else { - rc = 1; /* Delivered to the bitmap in shared_info. */ - /* Now switch to the vCPU's vcpu_info to set the index and pending_sel */ - read_unlock_irqrestore(&gpc->lock, flags); - gpc = &vcpu->arch.xen.vcpu_info_cache; + rc = 1; /* It is newly raised */ + } - read_lock_irqsave(&gpc->lock, flags); - if (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) { - /* - * Could not access the vcpu_info. Set the bit in-kernel - * and prod the vCPU to deliver it for itself. - */ - if (!test_and_set_bit(port_word_bit, &vcpu->arch.xen.evtchn_pending_sel)) - kick_vcpu = true; - goto out_rcu; - } + out: + read_unlock_irqrestore(&gpc->lock, flags); + return rc; +} - if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) { - struct vcpu_info *vcpu_info = gpc->khva; - if (!test_and_set_bit(port_word_bit, &vcpu_info->evtchn_pending_sel)) { - WRITE_ONCE(vcpu_info->evtchn_upcall_pending, 1); - kick_vcpu = true; - } - } else { - struct compat_vcpu_info *vcpu_info = gpc->khva; - if (!test_and_set_bit(port_word_bit, - (unsigned long *)&vcpu_info->evtchn_pending_sel)) { - WRITE_ONCE(vcpu_info->evtchn_upcall_pending, 1); - kick_vcpu = true; - } +static bool set_vcpu_info_evtchn_pending(struct kvm_vcpu *vcpu, u32 port_word_bit) +{ + struct kvm *kvm = vcpu->kvm; + struct gfn_to_pfn_cache *gpc = &vcpu->arch.xen.vcpu_info_cache; + unsigned long flags; + bool kick_vcpu = false; + + read_lock_irqsave(&gpc->lock, flags); + if (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) { + /* + * Could not access the vcpu_info. Set the bit in-kernel + * and prod the vCPU to deliver it for itself. + */ + if (!test_and_set_bit(port_word_bit, &vcpu->arch.xen.evtchn_pending_sel)) + kick_vcpu = true; + goto out; + } + + if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) { + struct vcpu_info *vcpu_info = gpc->khva; + + if (!test_and_set_bit(port_word_bit, &vcpu_info->evtchn_pending_sel)) { + WRITE_ONCE(vcpu_info->evtchn_upcall_pending, 1); + kick_vcpu = true; } + } else { + struct compat_vcpu_info *vcpu_info = gpc->khva; - /* For the per-vCPU lapic vector, deliver it as MSI. */ - if (kick_vcpu && vcpu->arch.xen.upcall_vector) { - kvm_xen_inject_vcpu_vector(vcpu); - kick_vcpu = false; + if (!test_and_set_bit(port_word_bit, + (unsigned long *)&vcpu_info->evtchn_pending_sel)) { + WRITE_ONCE(vcpu_info->evtchn_upcall_pending, 1); + kick_vcpu = true; } } - out_rcu: + /* For the per-vCPU lapic vector, deliver it as MSI. */ + if (kick_vcpu && vcpu->arch.xen.upcall_vector) { + kvm_xen_inject_vcpu_vector(vcpu); + kick_vcpu = false; + } + + out: read_unlock_irqrestore(&gpc->lock, flags); + return kick_vcpu; +} + +/* + * The return value from this function is propagated to kvm_set_irq() API, + * so it returns: + * < 0 Interrupt was ignored (masked or not delivered for other reasons) + * = 0 Interrupt was coalesced (previous irq is still pending) + * > 0 Number of CPUs interrupt was delivered to + * + * It is also called directly from kvm_arch_set_irq_inatomic(), where the + * only check on its return value is a comparison with -EWOULDBLOCK + * (which may be returned by set_shinfo_evtchn_pending()). + */ +int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, struct kvm *kvm) +{ + struct kvm_vcpu *vcpu; + u32 port_word_bit; + bool kick_vcpu = false; + int vcpu_idx, idx, rc; + + vcpu_idx = READ_ONCE(xe->vcpu_idx); + if (vcpu_idx >= 0) + vcpu = kvm_get_vcpu(kvm, vcpu_idx); + else { + vcpu = kvm_get_vcpu_by_id(kvm, xe->vcpu_id); + if (!vcpu) + return -EINVAL; + WRITE_ONCE(xe->vcpu_idx, vcpu->vcpu_idx); + } + + if (!vcpu->arch.xen.vcpu_info_cache.active) + return -EINVAL; + + if (xe->port >= max_evtchn_port(kvm)) + return -EINVAL; + + idx = srcu_read_lock(&kvm->srcu); + + rc = set_shinfo_evtchn_pending(vcpu, xe->port, &port_word_bit); + if (rc == 1) /* Delivered to the bitmap in shared_info. */ + kick_vcpu = set_vcpu_info_evtchn_pending(vcpu, port_word_bit); + srcu_read_unlock(&kvm->srcu, idx); if (kick_vcpu) {